I put one point into tempest when I reached 4th job. It's more helpful than you guys seem to acknowledge. =/

Besides, I don't follow guides when it comes to the 4th job. Getting mastery books is too difficult for me to bother with trying to pump up skills in any specific sequence. Right now, I'm getting as many of the skills as I can to at least level 10 the way I see fit; I won't get any stronger by stocking up on SP all for one skill I don't have mastery books for.

There's also one benefit to having even just 1 point into Combo Tempest, even after chaos.

Let's say you've managed to build up your combo meter to 200, and there are over 13 monsters surrounding you, top to bottom, left to right. Just position yourself somewhere in the middle, use tempest to freeze everything, and get your combo count to 50 or more. Then use combo recharge to get another 150 added to your combo count. Now you have 200 counts, AGAIN. Use tempest a second time while the monsters are still frozen from the first tempest. Now you have KOed over 13 monsters all around you in two attacks, and you didn't need to move an inch to do it.